Certified Rhythm Analysis Technician (CRAT) Practice Exam

The correct label for the augmented lead that typically shows a negative deflection is aVR. This lead is positioned to measure the electrical activity of the heart from the right arm, and its orientation is such that it generally captures signals that are moving away from the positive electrode. As a result, when the heart's electrical activity, represented by depolarization, primarily moves in a direction opposite to aVR, it produces a negative deflection. This characteristic of aVR is particularly useful in clinical settings, as it aids in the identification of certain cardiac conditions.

In contrast, aVL and aVF are oriented differently, measuring electrical activity with a more direct view towards the left arm and left leg, respectively, typically showing positive or smaller deflections. The aVC lead is not commonly referenced in standard 12-lead ECGs, and its defining characteristics do not align with the common understanding of augmented leads contributing to negative deflections. Understanding the positional characteristics and the vector nature of these leads is crucial for interpreting ECG readings accurately.